Various types of sliding bearings possessing self-lubricating feature have been developed; one of the important types being those made from a uniform porous structure via compacted and sintered metals formed by a technique known as powder metallurgy. In such sliding bearings to achieve a high porosity cannot balance a high density need for overall structural robustness and wear resistance of a bearing surface which is referred to a sliding surface for bearing relative rotation. In contrast, to achieve the high density cannot balance the high porosity need for sufficient lubricating media content. Hence to apply those to severe operating conditions, such as shaft rotating at high speed, heavy load and strong vibration, especially when contact pressure and velocity (PV) limit larger than 500 MPa·m/min will be subject to stern challenges. The lubricating media means lubricating oil and lubricant having a higher viscosity than the lubricating oil.